A suicide bomber drove a motorcycle into a convoy of U.S., NATO and Afghan forces on Monday, blowing himself up and killing six Americans, NBC News reported.
Two other Americans and an interpreter were wounded, U.S. officials said.
The service members were on a routine security patrol around outside Bagram Airfield north of Kabul around 1:30 p.m. local time when they were attacked, the official said.
U.S. officials did not specify the total number of Americans involved in the incident. The Taliban posted a message on Twitter claiming responsibility for the attack.
